In Mexican Mestizos the HCP5 rs2395029 SNP may be a genetic marker for screening abacavir hypersensitivity

Validation of two commercial real-time PCR assays for rapid screening of the HLA-B*57:01 allele in the HIV clinical laboratory

The pharmacogenetics approach to screen for the presence of the HLA-B*57:01 allele in HIV-1 infected patients is mandatory to prevent the potential development of hypersensitivity reaction to abacavir treatment. Given the limitations of current genotype methodologies, commercial real-time PCR assays were specifically developed for this purpose, but have not been sufficiently validated and are still not widely used. Here, in the context of the HIV laboratory, we assessed the ability of two commercial kits, the LightSNiP rs2395029 HPC5 assay (TIB Molbiol) and the Duplicα^Real-TimeHLA-B*5701 Genotyping kit (Euroclone), to retrospectively detect HLA-B*57:01 positive and negative samples of Israeli HIV-1 infected patients. The LightSNiP rs2395029 HPC5 assay had false-positive results, whereas the Duplicα^Real-Time HLA-B*5701 Genotyping kit was highly accurate and could be readily implemented into clinical practice. It is hoped that this study will facilitate the assessment of additional commercial kits for HLA-B*57:01 detection and expand their use in the clinical laboratory. Such studies can likely help the use of abacavir treatment in HIV-1 infected patients.

The frequency of HLA-B(∗)57:01 and the risk of abacavir hypersensitivity reactions in the majority population of Costa Rica

HLA-B(∗)57:01 is a well-known and cost-effective pharmacogenetic marker for abacavir hypersensitivity. As with other HLA alleles, there is widespread variation in its frequency across populations. The Costa Rica Central Valley Population (CCVP) is the major population in this country. The frequency of HLA-B(∗)57:01 in this population has not been described yet. Thus, our aim was to determine the frequency of this allele in the CCVP. 200 unrelated healthy volunteer donors born in the CCVP were typed. HLA-B(∗)57-positive samples identified by HLA intermediate resolution typing methods were further typed by SBT to high resolution. An HLA-B(∗)57:01 carrier frequency of 5.00% was determined in this sample. This frequency is relatively high in comparison to reports from other populations in Latin America. These results suggest that there is a considerable frequency of HLA-B(∗)57:01 in the CCVP and that pharmacogenetic testing for HIV+ patients who are going to receive abacavir-based treatment should be considered in this country.

Development of multiplex pyrosequencing for HLA-B*57:01 screening using single nucleotide polymorphism haplotype

WHAT IS KNOWN AND OBJECTIVE

Abacavir (ABC) is a commonly used nucleoside reverse-transcriptase inhibitor with potent antiviral activity against HIV-1. The US Food and Drug Administration and international HIV treatment guidelines recommend HLA-B*57:01 screening before initiating treatment with ABC. The current standard method for HLA-B*57:01 screening is limited by its high-cost, time-consuming and labour-intensive procedure with the requirement of a specialized laboratory. Our study aims to develop a more reliable screening test by selecting rs3093726 as an additional single nucleotide polymorphism (SNP) to combine with rs2395029 for multiplex pyrosequencing development. It offers high-accuracy, cost-effective and rapid detection.

METHODS

Multiplex pyrosequencing was developed for HLA-B*57:01 screening using rs2395029 and rs3093726 as a surrogate marker and tested in 130 Thai subjects in parallel with singleplex pyrosequencing of each SNP and the standard sequence-based method.

RESULTS AND DISCUSSION

Multiplex pyrosequencing showed 100% concordance when compared with both singleplex pyrosequencing and standard sequence-based method. This method showed 100% of negative predictive value (NPV), positive predictive value (PPV), specificity and sensitivity.

WHAT IS NEW AND CONCLUSION

Multiplex pyrosequencing is a powerful tool for HLA-B*57:01 screening using the rs2395029 and rs3093726 haplotype genotyping as surrogate marker for this HLA-B. The assay provides accurate, cost-effective and rapid detection of this haplotype. It can be applied for ABC hypersensitivity screening of the Thai population before initiating treatment with ABC.